window.onload = function() {
    var Fen = document.getElementById("fenxiang"); //获取到页面元素
    var Bg = document.getElementById("bg"); //添加点击事件
    Fen.onclick = function() {
        Bg.style.display = "block"; //点击页面出现遮罩层
    }
    Bg.onclick = function() {
        Bg.style.display = "none"; //点击遮罩层，遮罩层消失
    }
}